FCOM: 22 - Autoflight

Question 1

What is the minimum use height for the autopilot on takeoff?

Answer 1

100ft AGL and 5 secs after lift off.

22/10/24

Question 2

What is the minimum height for the autopilot when using:
- FINAL APP
- V/S or FPA
- ILS CAT 1
- Circling approach

Answer 2

• FINAL APP: 250ft
• V/S or FPA: 250ft
• ILS CAT 1: 160ft
• Circling approach: 500ft

22/10/24

Question 3

In the FMGC, what is mean by recommended max?

Answer 3

The lowest altitude of all of these:
- 0.3G buffet margin
- maintaining level flight with MAX CRZ
- 300fpm rate of climb in MAX CLB
- where a speed between green dot and VMO/MMO can be maintained

23/10/24

Question 4

What is a good gross error check for calculating green dot?

Answer 4

Below 20,000ft, 2 x mass (tonnes) + 85
Above 20,000ft add 1kt per 1000ft

15/06/24

Question 5

On some aircraft, there can be a discrepancy between Vapp on the PFD and that on the FMGC. Why?

Answer 5

The FMGC calculates Vapp based on the weight entered into the MCDU. The PFD displays Vapp based on calculated weight from the FACs.

23/10/24

Question 6

When is the autoland light armed?

Answer 6

Below 200ft, and with at least one AP engaged.

23/10/24

Question 7

Briefly explain how groundspeed mini works.

Answer 7

Vapp is corrected by the GS Mini function.
GS Mini maintains aicraft energy above above a minimum level that will provide standard stall margins.
The aircraft energy is that at touchdown at Vapp, corrected for the wind (as inserted in PERF APPR page).
Therefore the inputs are: tower headwind component (from ATC), current headwind component (from ADIRS), and Vapp (calculated by the FMS).
The formula is:
Managed speed target = Vapp [FMS] + (headwind [ADIRS] - headwind [TWR].

25/09/24

Question 8

How does the aircraft determine its position?

Answer 8

Each FMGC computes its own position from:
- a MIX IRS position & a computed radio position; or
- a GPS position.

23/10/24

Question 9

What is EPE?

Answer 9

Estimated Position Error. The estimated nab accuracy, as computed by the FMS.

23/10/24

Question 10

What is meant by GPS PRIMARY?

Answer 10

There are two factors that are meant by “GPS PRIMARY”:
- Accuracy (which will be HIGH)
- Integrity (the ability to internally detect a failure).

23/10/24

Question 11

With a loss of both FMGCs how do you recover radio navigation?

Answer 11

Using NAV backup mode

23/10/24

Question 12

For holding, what does the IMM EXIT button do?

Answer 12

Prior to entering the hold, the aircraft will not enter the hold and will continue on the flight plan route.
In the hold, the aircraft will return immediately to the hold fix and resumes the flight plan route.

23/10/24

Question 13

For alternate planning, what assumptions are made for flight level and speed by the FMGC in terms of the fuel burn for the alternate?

Question 14

Explain SRS.

Question 15

Are there any protections with SRS?

Question 16

What would happen when selecting a revised altitude when the aircraft is in ALT*?

Question 17

What is the two engine operating range of the autothrust?

Question 18

What is the single engine operating range of the autothrust?

Question 19

With autothrust failure, what FMA would you expect to see?

Question 20

If you took off in flex, how do you achieve MCT in an engine failure after takeoff?

Question 21

What is the guidance for selecting reverse thrust with one reverser inop?

Question 22

If you move the thrust levers below the climb detent what FMA would you expect to see?

Question 23

What is the maximum speed that you can set on the FCU?

Question 24

What is the minimum speed that you can set on the FCU?

Question 25

What is the backup speed scale, when might you need to use it, and where is its data derived?

Question 26

Explain the bird and where it gets its data from.

Question 27

Explain “data lock”.

Question 28

What is LAND mode?

Question 29

What would cause the autoland light to illuminate?

Question 30

What is the definition of alert height?

Question 31

Would the failure of a single engine illuminate the Autoland light?

Question 32

How does the FMGC Compute Vapp?

Answer 32

Vls + ⅓ of headwind component
Vapp should be between Vls + 5kt and Vls + 15kt

31/05/24

Question 33

How is Vls calculated?

Answer 33

Vls is calculated by the FAC, based on aerodynamic data and it is:
1.13 VS (take off, touch & go)
1.23 VS after retraction of 1 stage of flaps
1.28 VS in clean configuration
Above 20,000ft, Vls is corrected for Mach effect to maintain a buffet margin of 0.2g

15/06/24

Question 34

What does optimum mean on the MCDU cruise page?

Question 35

What is the relationship between V2 and VS1G?

Answer 35

V2 is 1.13 x VS1G.
explanation: all aeroplanes are flight-tested to see what the stall speed is at a load factor less than 1G. This gives a speed which is noted as VSmin. Because of the low speed protection feature, during certification of the A320 series, the authority allowed Airbus to use a factor of 0.94 x VS1G as VSmin. As V2 is always 1.2 x VSmin (for non Airbus aircraft), this means that for the A320 series, V2 can be 1.2 x 0.94 x VS1G = 1.13

25/08/2024

Question 36

What is Vref?

Answer 36

On an aircraft without low speed protection, it would be 1.3 x VSmin. But because of low speed protection, on the A320 series, Vref is allowed to be 1.23 x VS1G

25/08/24

Question 37

What is the relationship between VSmin, VS1G, V2 and VLS

Answer 37

We start with VSmin (stall speed).
Because of low speed protection, we are able to use a speed lower than VSmin as a reference for all of our operating speeds. This is VS1G. It is 0.94 x VSmin.
V2 is 1.13 x VS1G
VLS is 1.13 x VS1G on take off or touch & go
VLS becomes 1.23 x VS1G after retracting 1 stage of flaps
VLS becomes 1.28 x VS1G in clean configuration.

Question 38

What is the relationship between VLS and VMCA?

Answer 38

VLS is never less than 1.05 x VMCA.

09/10/24

Question 40

What is nav accuracy telling us?

Answer 40

Nav accuracy is comparing the EPE (Estimated Position Error) with the RNP (Required Navigation Performance). If the EPE is better than RNP, nav accuracy is HIGH. If not, then it is LOW.

09/10/24